make show-index a builtin

The git-show-index command is built as its own separate
program. There's really no good reason for this, and it
means we waste extra space on disk (and CPU time running the
linker). Let's fold it in to the main binary as a builtin.

The history here is actually a bit amusing. The program
itself is mostly self-contained, and doesn't even use our
normal pack index code. In a5031214c4 (slim down "git
show-index", 2010-01-21), we even stopped using xmalloc() so
that it could avoid libgit.a entirely. But then 040a655116
(cleanup: use internal memory allocation wrapper functions
everywhere, 2011-10-06) switched that back to xmalloc, which
later become ALLOC_ARRAY().

Making it a builtin should give us the best of both worlds:
no wasted space and no need to avoid the usual patterns.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 86 insertions, 0 deletions

diff --git a/builtin/show-index.c b/builtin/show-index.c
new file mode 100644
index 0000000000..a6e678809e
--- /dev/null
+++ b/builtin/show-index.c
@@ -0,0 +1,86 @@
+#include "builtin.h"
+#include "cache.h"
+#include "pack.h"
+
+static const char show_index_usage[] =
+"git show-index";
+
+int cmd_show_index(int argc, const char **argv, const char *prefix)
+{
+	int i;
+	unsigned nr;
+	unsigned int version;
+	static unsigned int top_index[256];
+
+	if (argc != 1)
+		usage(show_index_usage);
+	if (fread(top_index, 2 * 4, 1, stdin) != 1)
+		die("unable to read header");
+	if (top_index[0] == htonl(PACK_IDX_SIGNATURE)) {
+		version = ntohl(top_index[1]);
+		if (version < 2 || version > 2)
+			die("unknown index version");
+		if (fread(top_index, 256 * 4, 1, stdin) != 1)
+			die("unable to read index");
+	} else {
+		version = 1;
+		if (fread(&top_index[2], 254 * 4, 1, stdin) != 1)
+			die("unable to read index");
+	}
+	nr = 0;
+	for (i = 0; i < 256; i++) {
+		unsigned n = ntohl(top_index[i]);
+		if (n < nr)
+			die("corrupt index file");
+		nr = n;
+	}
+	if (version == 1) {
+		for (i = 0; i < nr; i++) {
+			unsigned int offset, entry[6];
+
+			if (fread(entry, 4 + 20, 1, stdin) != 1)
+				die("unable to read entry %u/%u", i, nr);
+			offset = ntohl(entry[0]);
+			printf("%u %s\n", offset, sha1_to_hex((void *)(entry+1)));
+		}
+	} else {
+		unsigned off64_nr = 0;
+		struct {
+			unsigned char sha1[20];
+			uint32_t crc;
+			uint32_t off;
+		} *entries;
+		ALLOC_ARRAY(entries, nr);
+		for (i = 0; i < nr; i++)
+			if (fread(entries[i].sha1, 20, 1, stdin) != 1)
+				die("unable to read sha1 %u/%u", i, nr);
+		for (i = 0; i < nr; i++)
+			if (fread(&entries[i].crc, 4, 1, stdin) != 1)
+				die("unable to read crc %u/%u", i, nr);
+		for (i = 0; i < nr; i++)
+			if (fread(&entries[i].off, 4, 1, stdin) != 1)
+				die("unable to read 32b offset %u/%u", i, nr);
+		for (i = 0; i < nr; i++) {
+			uint64_t offset;
+			uint32_t off = ntohl(entries[i].off);
+			if (!(off & 0x80000000)) {
+				offset = off;
+			} else {
+				uint32_t off64[2];
+				if ((off & 0x7fffffff) != off64_nr)
+					die("inconsistent 64b offset index");
+				if (fread(off64, 8, 1, stdin) != 1)
+					die("unable to read 64b offset %u", off64_nr);
+				offset = (((uint64_t)ntohl(off64[0])) << 32) |
+						     ntohl(off64[1]);
+				off64_nr++;
+			}
+			printf("%" PRIuMAX " %s (%08"PRIx32")\n",
+			       (uintmax_t) offset,
+			       sha1_to_hex(entries[i].sha1),
+			       ntohl(entries[i].crc));
+		}
+		free(entries);
+	}
+	return 0;
+}